RETIREMENT PLANS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Pension plan defined benefit plan cost increase limit percentage (in hundredths)	4.00%
Pension Plan [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	$ 2,767	$ 3,171
Interest cost	3,223	2,835
Expected return on plan assets	(4,713)	(4,027)
Amortization of actuarial gain	196	2,056
Net periodic benefit cost	1,473	4,035
SERP [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	0	0
Interest cost	18	17
Expected return on plan assets	0	0
Amortization of actuarial gain	4	5
Net periodic benefit cost	22	22
Other Postretirement Benefits [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	0	0
Interest cost	28	28
Amortization of actuarial gain	(163)	(155)
Net periodic benefit cost	$ (135)	$ (127)